What's the function of C in a RCD clamping snubber network?

[hithesh123]

I don't understand the function of C in a RCD clamping snubber network.
Also, when does(at what voltage) RCD start conducting?
Can someone explain please.
I read the TI app note, but still dont get it.

 

[dick_freebird]

C has to soak up the inductor energy on the edges and
block the DC voltage. R dissipates edge energy from the
tank, preventing ringing. D recirculates current and/or
"resets" the capacitor.

 

[hithesh123]

C has to soak up the inductor energy on the edges and
block the DC voltage. R dissipates edge energy from the
tank, preventing ringing. D recirculates current and/or
"resets" the capacitor.

Can you please elaborate.
C will conduct during Voltage change(dv/dt) and block during steady state?
But the resistor will conduct during DC. Will it not result in loss?
How does D reset the cap?

 

[mtwieg]

In a RCD clamper, the diode only conducts during overshoot. The capacitor is charged to the clamp voltage during overshoot, so it stores the excess energy during that brief time. The function of the resistor is to discharge the capacitor back to near the nominal drain voltage, so that by the next turn-off it is ready to clamp again. So yes, the resistor will dissipate some power. But this can be avoided somewhat by connecting the resistor to the output instead of ground (so that some of the power is delivered to the output and not wasted). In general clamping snubbers are meant to protect device failure, not improve efficiency.